Safety regulations concerning the operation of elevators require a progressive safety on an elevator car or on its counterweight. A progressive safety decelerates an elevator when the elevator's speed exceeds a predetermined value. The deceleration increases with distance traveled by the elevator, thereby comfortably slowing the elevator.
One of the more popular progressive safeties is that disclosed by Koppensteiner in U.S. Pat. No. 4,538,706. Koppensteiner discloses a safety device which straddles an elevator rail. The device employs a brake surface on one side of the rail and a leaf spring and roller assembly on the opposite side. When the elevator governor activates the safety, the roller wedges in between the leaf-spring assembly and a rail face. As a result, the brake lining located on the opposite side of the rail contacts the opposite rail face, producing a braking force on the elevator car. To ensure that the roller properly wedges between the leaf-spring assembly and the rail face, Koppensteiner teaches that a section of the roller face should be knurled. The knurling increases the coefficient of friction between the roller face and the elevator rail. The direct contact of the knurled roller and the brake surface with the rail faces, however, may result in a scored and damaged rail.
A scored rail face causes several problems. In an elevator with sliding guides, scored rails will damage the guides resulting in a decrease in guide life. Similarly, scored rails may also affect the smoothness of the elevator ride as well as create undesirable running noise. Elevators with roller-type guides are also susceptible to these problems when the rails become scored.
Prior art methods of rehabilitating a scored rail include hand filing the scored section and subsequently filling the indentation or pits with a filler material such as lead. One disadvantage of this method of repair is that the rail is compromised by using a softer filler material which is more susceptible to later scoring. Another disadvantage lies in the build-up of debris that occurs as the softer material wears due to the movement of the guides.